The potential vaccine comes as U.S. drug overdose deaths continue to soar. Researchers from the Centers for Disease Control and Prevention found that heroin overdose death rates have more than quadrupled since 2010. There were nearly 13,000 reported fatalities from a heroin overdose in 2015 alone. In 2010, only eight percent of drug overdose deaths involved heroin; in 2015, 25 percent did.

“The continuing rise in death rates related to heroin use and synthetic opioids is of great concern,” said Dr. Larissa Mooney, assistant clinical professor of psychiatry at the University of California, Los Angeles, and director of the university’s Addiction Medicine Clinic.

The vaccine works by exposing the immune system to part of the heroin molecule. As with vaccines against viruses, this teaches the immune system to produce antibodies. In this case, the antibodies are against heroin and its psychoactive products. The antibodies then neutralize the molecules, blocking them from reaching the brain to cause feelings of euphoria.

“The vaccine sequesters the psychoactive molecules that heroin produces and prevents distribution to the brain,” explained Paul Bremer, a graduate student at The Scripps Research Institute and first author of a study about the vaccine. “It essentially uses your body’s own natural defenses to neutralize the drug.”

Because it is tailored specifically to heroin’s molecular structure, this vaccine works only against heroin, not other opioid-based painkillers or medications for treating opioid addictions or overdose. A potential downside of the vaccine is that it does not help in suppressing people’s cravings for a high during withdrawal, so there is concern individuals could turn to other drugs for a similar high.